1. Field of the Invention
The present invention relates to an image-forming device.
2. Description of Related Art
A laser beam printer disclosed in Japanese unexamined patent application publication No. 2001-146355 forms images using an electrophotographic system. The electrophotographic system forms images by first applying a uniform charge over the surface of a photosensitive member, and exposing the photosensitive member to a laser beam irradiated by an optical mechanism, such as a scanner. The surface of the photosensitive member is selectively exposed based on image data to form an electrostatic latent image. This latent image is developed into a toner image. Subsequently, the toner image borne on an image-bearing member (the photosensitive member or an intermediate transfer member) is transferred onto a recording paper. The transferred image is fixed onto the recording paper as the recording paper passes through a nip part formed between a heating roller and a pressure roller in a fixing unit.
An image-forming device disclosed in Japanese unexamined patent application publication No. 2001-255768 focuses on the relationship between the softening point of toner and an angle of separation. The angle of separation is defined within a plane orthogonal to the central axis of the heating roller. The angle of separation is defined as an angle between the direction in which the recording paper is discharged from a downstream end of the nip part and a tangent to the heating roller at the downstream end in the nip part. This image-forming device sets the angle of separation and the softening point of the toner to satisfy a predetermined relationship in order to minimize the amount of curl generated in the recording paper.